Reciprocating Endodontics — ORE Part 1 MCQ

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ModerateEndodonticsReciprocating EndodonticsORE Part 1

When choosing a reciprocating single-file nickel-titanium system rather than a continuous-rotation system for root-canal preparation, which advantage is most characteristic of the reciprocating motion?

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Correct answer: A — Greater resistance to cyclic fatigue

Explanation lettering: E = shown as B · B = shown as D · D = shown as E

A is correct. Alternating forward and reverse movement reduces the cumulative tensile-compressive stress imposed on a nickel-titanium file in a curved canal, giving reciprocating instruments greater resistance to cyclic fatigue than continuous-rotation instruments. This is the characteristic mechanical advantage, although actual fracture risk also depends on alloy, file design, canal curvature and use. Irrigation remains essential for disinfection and debris removal, and working length must still be established before preparation, so B and C are incorrect. D and E are not universal advantages: preparation speed and cutting efficiency vary with the individual system, canal anatomy and operator technique rather than following inevitably from reciprocation.

Reference: De Pedro-Muñoz A, Rico-Romano C, Sánchez-Llobet P, et al. Cyclic Fatigue Resistance of Rotary versus Reciprocating Endodontic Files: A Systematic Review and Meta-Analysis. Journal of Clinical Medicine. 2024;13(3):882. https://pubmed.ncbi.nlm.nih.gov/38337577/